Stereoscopical color photography



C. MULLER ET AL STEREOSCOPICAL COLOR PHOTOGRAPHY Jan. 24, 1928.

Filed Nov. 26, 1924 4 Sheets-$heet 2 .Tan. 21, T928. 1,657,270 7 C. MULLER ET AL STEREOSCOPICAL coLdR PHOTOGRAPHY Filed Nov. 26, 1924 4 sheets-sheet 5 Fig.7. I U I, Fig.8.

Jan. 24,1928. 1,657,270

' C. MULLER ET AL STEREOSCOPICAL COLOR PHOTOGRAPHY I Filed Nov. 26. 1924 Fig. 13 "W 4 Sheets-Snot 4 Fig.14. I

80 7.9 a! g V 85 wm'flmwmn wa /r Patented Jan. 24, 1928.

UNITED STATES PATENT OFFICE.

CARL MULLER AND ELSA. MI TLLER, OF CHARLOTTENBURG, NEAR BERLIN, GERMANY,

ASSIGNORS TO KARL MEY,

OF BERLIN, GERMANY.

Application filed November 26, 1924,

Our inv ntion relates to stereoscopical color photography and has for its purpose to simplify the production of the stereoscopically co-ordinated images from which the impression of an object in natural colors is to be built up. To this end our invention consists in certain novel steps of producing the partial images which are 'required.

In order that our invention may be fully understood by persons skilled in the art we shall describe it with reference to the annexed drawings whichmerely diagrammatically show constructional means for producing partial images for stereoscopical color photography and diagrams relating to the selection of colored light to be used in the photographic exposures.

In Figure 1 we have shown an arrange ment for producing two sets of photographic images from an object to be reproduced in natural colors through two objectives and co-ordinated prism devices, the one set containing three images and the second. set taken through the second objective laterally displaced with relation to the first named objective containing one image only.

Figure 2 illustrates the transforming and uniting of the four with the device of image.

Figure 3'il'lustrates the compounding of two partial images to one single image on a screen by projection and the dissolving contemplation by theeyes of an observer.

Figure 4 shows a modification of the departial images produced Figure 1 into one single vice of Figure 1 allowing the production of f two sets of partial images through two lat erally displaced objectives, each set consisting of two different images.

Figure 5 shows adevice for'directly pro ducing a compound image combining a plu-.

rality of partial images showing difi'erent aspects of the object.

Figure 6 shows a modification of the device illustrated in Figure 5.

Figures 7 to 12 illustrate different kinds of co-ordination of colors for use in the production of partial image's.

Serial No. 752,396, and in Germany August 4, 1921.

shows an arrangement for stereoscopical color cinematography.-

Figure 16 shows a modification of the filter arrangement of Figure 6 for cinematographic exposure.

In Figure 1 two objectives are designated 1. 2 and prism devices co-ordinated to said objectives 3, 4. The prism device 3 which is tnown per se is adapted to divide the light passing through the objective 1 into three divisions, each of which is adapted to produce a separate image of an object sending rays of light through the objective 1; these three images being produced on sensitive layer carriers 5, 6, 7. A further image of the same object is produced by objective 2 and prism 4 on a sensitive layer carrier 8.

nterposed between the sensitive layer carriers 5 to 8 and the prism devices 3, 4: are color filters 9 to 12.

The colors of the filters 9 to 11 are preferably so chosen that they correspond to the fundamental colors of the spectrum whereas the color filter 12 may be of any color and may even be entirely omitted.

The insertion of the color filters 9 to 12 has the effect that'the light beams passing through the prism devices produce different impressions on the sensitized layer carriers. ordinary pan-chromatic plates are used then ordinary black white pictures are ob tained.

If now the black white brought to: projection on a screen 13 as illustrated in Figure 2 and if the projecting light beams for each picture are suitably colored in dependence from the color of the filters 9 to 12 then the compound image 14 on the screen can be, dissolved on inspection with spectacles having two differently colored glasses into two images, each presented only to one eye of the spectator and the two pictures 5 to 8 are images producing together the impression of the stereoscopic image of the object in natural colors.

In Figure 2 of the drawing the colored light for projection of the pictures 5 to' 8 is produced by inserting of color filters 15, 16, 17 18 into the path of light rays coming from a source of light 19. A lens arrangement 20 and 21 to 24 being provided for suitably controlling of the direction of rays of light before impinging on the pictures 5 to 8. The projection objectives are designated 25 to 28.

Preferably the colors of the filters 15 to 17 are substantially the same as the colors of the filters 9 to 11 through which the pictures were taken, however with exclusion of at least one limited portion of the spectrum, this limited portion of the spectrum fully or partly corresponding to the color of the filter 18. The coloration of the lenses of the spectacles for inspection above mentioned.

are to be so chosen thatone glass is substantially permeable for the colors of the filters 15--17,. but impermeable for the color of filter permeable for light in the color voffilter 18 and impermealil; for light in the colors of filters 15- If the colors for the filters and eye glasses are selected in this way then the one eye of the observer has communicated to it an image of the object containing all the three fundamental colors of the spectrum whereas theother eye receives an unage which before all has the effect to supplement the said colored lmage presented to the one eye so as to make it astereoscopic one.

, image containing i I color of the filter The presentation all three fundamental colors of the spectrum has the valuable eifect that a conflict of the colors with each other is avoided. Moreover the compound image containing the three images of the object taken from the. same position may be used without the s'tereoscopically co-ordinated fourth image as a normal image of the object in natural colors. 1

Suitable colors for the filters 9 to 11 are the usual colors for the light filters in three color photogrzfphy whereas filters 15" to 17 used in the projection of the black white pictures may preferablyv be colored for instance red, blue-green and blue. \Vith these colors for the filters 15-17 the color of filter 18 is preferably yellowish green. The 12 is similar to that of the filter 18, it being however immaterial if A further suitable color the colorcomprises a little more or less of thisregion of. the spectrum or if it even contains still some other portions of the spectrum. Y

combination for the filters 15'to 17 is red, yellowish green and blue, the-filters 9 to 11 being again in used for filter 18; however ordinarily tothe one eye of an.

the fundamental colors of the spectrum In this case the filter 18 is preferably blueish green and the filter 12 again similar to filter 18. Filter 18 may also be colored in a color corresponding to a region of the spectrum intermediate two fundamental colors for instance orange, yellow, greenish-yellow or greenish blue. The coloration of the fil ter 18 may also contain colors corresponding to regions of the spectrum intermediate each two fundamental colors. Besides said intermediate regions of. the spectrum the coloration of filter 18 may contain such colors which supplement them to a substantially neutral or whitish color. In all cases care should be taken to co-ordinate the lightpermeability of the filter 18 and. the quantity of light with which it is fed in such manner that a sufliciently luminous image is obtained.

The filters 15-17 should be colored substantially in the fundamental colors of the spectrum except the region of the spectrum the region of the spectrum covered by filter 18' may, if desired, somewhat overlap theregions corresponding to the other filters.

Instead of throwing all four images simultaneously on' a screen so as to form a compound image they can lee-thrown singlyor 111 arbitrary'combinations in quick succession on the screen. A quick change in color and a division of the projecting light into two color mixtures which are complementary to each other may be obtained. by use of polarizing devices. With such devices a beam of light is divided in a double refracting prism into two differently polarized partial beams Which by insertion of a double refracting crystal plate for instance a plate of crystallized calcium sulfate and a further eventually double refracting prismcan be acted on so as to form complementary colored beams of light.

Instead of direct inspection of the image 14 on a screen 13 at first a colored compound picture can be formed which may be used for being-projected on a screen. Such compound picture offers the convenience that the complicated projection device for projecting and superposing of the partial images can be dispensed with.' Such compound picture can for instance'by projecting the beams of colored light passing through the objectives 25 to 28 on a sensitized layer adapted for the production of colored pictures by means of a bleaching method. sensitized layer provided with a color screening, the color elements of which be- .ing colored substantially in the colors of the Of course instead of one One can also use a picture on a screened senwithout screening homogeneously colored 1 in one single color only.

In the production of tures on color screened sensitized layers the color elements of the screened layers and the colors of the filters1518 controlling the color of. the light should be preferably selected with respect to the colors of the light filters 9 to 12 through which the pictures 5 to 8.Were originally taken.

The interdependence between the colors of the filters 9 to 12 and those of the color elesuch compound pic ments of a screened sensitive layer whereon' a compound picture is to some special embodiments illustrated in Figures 7 to 11. Inthese figures the arcs shown in full lines represent the regions of the spectrum covered by the colors of the filters 911, whereas the arcs shown in dotted lines illustrate the regions of the spectrum covered by the color elements of the screened sensitive layer.

Figures 7 and 8 show an arrangement ac cording to which the regions of the spectrum covered by the screen elements are not totheir full extent covered by the such additional be made is for filters; regions being either arbitrarily positioned (Figure 7) or adjacent.

to the region of the filters (Figure 8).

In the examples of Figures 9 to 11 the color regions of the screen elements are overlapping each other this resulting in greater brilliancy of the images.

In Figure 9 the color regions of the filters likewise are overlapping each other, but not to the same extent as the screen ele ments. Furthermore they also overlap the color regions of the screen elements.

In the examples of Figures 10 and 11 the color regions of the filters are so selected that thelight of each filter can only pass through one set of screen elements; Figures 10 and 11 are however distinguished in this that in Figure 11 the color region covered by each of the filters is more limited than that of the color region of the co-ordinated screen clement-s.

The effect of the color selection represented in Figures 10 and 11 is superior to that of Figure 9 in this, that a more correct color reproduction is obtained. This is due to the fact'that although the colors of the screen elements overlap each other, each screen element allows passing of light which had y a color screened sensitized layer passed one of the filters 5 to 7 only the colors of which are identical with those of the printing filters 15, 16, 17.

Instead of printing the images 5 to 8 on it is possible to print the several pictures on ordinary sensitized layers, f. i.- as positives on cause it is difficult to thin transparent layers of gelatine or the like and to superpose' such thin transparent layers after dyeing with colors which are substantially complementary to the colors of the filters 15 to 18. If such compound images are presented to the eyeof an observer then an impression of the natural colors of the object is produced, according to the so-called subtractive method Whereas the pictures on the color screened sensitized layer result in the reproduction of the object according to the so -called additive method.

Instead of printing the four elementary pictures 5 to 8 on the same, screened sensitized surface one could produce two separate prints, the 9ne combining f. i. the pictures 5 to 7 on a screened surface whereas the second would consist of a simple posit'ive of the picture 8. In this case it would be possible to use the prints on the three color screened surface .as a non-steroscopic reproduction of the object in natural colors.

One could also print the pictures 5 to 8 on two different screened sensitized layers in this arrangement that one compound picture is formed combining f. i. the pictures 5, 6 and a further picture combining the pictures 7, 8. This facilitates the printing, be-

produce colored screened sensitized layers with more than two sets of differently colored screen elements. An arrangement of producing two pairs of partial'images of the object to be stereoscopically reproduced in natural colors is illustrated in Figure 4:. In this figure the numerals 29 and 30 designate two objectives and the numerals 31, 32 two light dividing prism devices, the numerals 33, 34, 35, 36 designate four pan-chromatic sensitized layers and the numerals 37, 38, 39 and 40 four light filters co-ordinated to the sensitized plates 33 to 36. I The lightfilters 37 to 402mm preferably colored respectively red, green, green and blue. Images are taken from the object by the ob]ect1ves 29, 30 through prism devices 31, 32 and light filters 37 to 40,-each of the resulting two pairs of black white partial images 33, .34 and 35, 36 is printed on a two color screened surface using a device similar to that of F1gure2. In this way two compound pictures are obtamed, each. picture. giving a certain color aspect of the object from one position, the two positions different fromeach other as required for producing a stereoscopical efect. Assuming that the pictures 41 and 42 of Figure 3 are the compound pictures pro- Figure 3 then the compound projection image 43 can be divided up'by suitable color 42 are supe r' projection as illustrated in selectors 45 into two images giving colord from difaspects'of the ob1ect contemplate ,ferent points of v ew so that theeyes 46, 47

- of an observer receive object course depends colors.

tures one set of screen elements is dyed in the 7 color which is used in'ea'ch of the two pairs the colors of the of -partial images and the-other set in the mixed color of the two other fundamental It has. already been said that the exposition of the sensitised layers 33 to 36 -is preferably cffectedthrough color'filters 37 to 40 in red, green, green and blue respectively. In order to get from white partial images suitably colored screened images 41, 42,- the. images may be printed with light of substantially the same colors as those with which they were taken, the printing preferably taking place on identically color screened sensitive layers,

screen' erably purple duce from such two color screened pictures 41 and 42a compound image43, the stereoscopically co-ordinated elementary'images ofwhich can be brought to correct perception .by the eyes ofan observer so as to the impression of the corporal objectin natural-colors; the projection of pictures 41 and 42 should be effectedthrough light" filters 48, 49, the formercomprising the colors red and yellowish een and the latter the colors blue and blueish green, or. the former red and blueish green and thelatter blue and yellowish green. The glasses 44, of the spectacles with whichthe compound image screened image-and images 34 and-36 inthe are for-instance 'red, yell 43 is 'to be inspected should 'be similar 1n coloration to the filters 48, 49. It is also possible to combine images 33' and 35 in one second screened image. Provided that in this case'the-light projection filters48, 49 I v owish green and hlue+blueish green respectively, the colors of thecolor selectors 44, 45 should be red+ blueish green and blue+ yellowish green. I

The color-effect of the compound image-43 is what is. called an additi-ve one.

The two pairs of pictures;33, 34 and 35, 36 can alsohe used for'the stereoscopical re; production" of theobiect. in conformity with a subtractive method. For this purpose the pairs of pictures 33, 34 and 35,

rs for the four for both compound picthese obtained black-- elements being pref-' and' green. In order to pro'- build up 36 should be printed onan ordinary. light sensitive plate so as to produce ordinary positives thereof.' The positives should be produced on transparent films and the films dyed in this way that the positives of the pictures 33 and 36 are dyed in a color mixture of the two colors with which the pictures 34 and 35 had been taken (f.- i..green) whereas the transparent positive films of the pictures 34'and 35 are dyed in the colormixture of the colors with which the sensitive layers for the pictures 33 and 36 had been exposed (f. i. purple= red+blue). Thedyed tive images of the pictures 33 and 36 an the films with the positives of the pictures that on the one hand images 33 and 34 and on the other hand images 36 and 35 are in superpositiom .The compound-films form substitutes v of the pictures 41 and" 42 0f vFi, ;'ure 3 and can be proj colored light of the light filters 48 and 49 as described with reference to Figure ,3. It results a compound image corresponding to the image 43 of Figure 3 which vided' up into. two aspects of the object from di'iferent points can be di-' images, giving color v films with'the posi-f 34 and 35 are superposed in such manner ected with the of view so as to producewhen presented to the eyes of the observer through. the color, selectors '44, 45 a stereoscopic imageof the object in natural colors according to the sub tractive method.- Instead of producing a compound image by projection for being divided up by. color selectors,one can use the pictures 33 to 36 for producing printed colored pictures forl direct inspection, may 1t be in a ster'eoscope or with color separating spectacles. In order ,to' obtain printing plates for such pictures the pictures 33 to 36 are printed on sensitive-layers f..i.' with interposition of a screen as ordinarilyused in three-color printing. ,The printing plates so produced from the pictures 33'and36 are combined to a compoundprinting plate which shows the positive of the picture 36 onthe left side and that of. picture 33 'on the right side. I I

In the same'way 34 and 35 are combined'to a printing plate. Each of the two eompoundpri-nting plates soproduced is inked with a'colormlxture containing the colors of the light filters through which'thenegatives for the printmg lates of the'elementary; pictures of the other printing plate had been taken, that is to say, provided the pictures'33 to '36 had been taken with red, green, green and blue 4 light res actively, the printing plate con tainmg t e positives of the pictures 33 and '36is inked with green colorand the rintg ing plate containing thevpositives 0 pictures 34 and 35 is inked'with purple color.

two difierently. colored sections- 1 the positives of the pictures f ow the two compound'prmtin'g plates are T The coloring of that section of the surface I on which the positives of the pictures 36 and 35 are printed, being substantially a mixture of the colors with which the negatives35 and 36 had been taken (f. i. green and blue) and the coloring of the portion of the surface on which the positives of the,

pictures 33 and 34 are printed in superposition being substantially a mixture of the colors with which the pictures 33 and 34 had been taken (f. i. red and green).

Instead of producing at first partial images of the object in black white and eyes being stereoscopically co-ordinated so.

plate 55. The objective 54- is using these black white images for the production of a colored compound image it is possible to produce at once in one single step colored images by exposing of a color screened sensitive layer. Devices for working in this way are illustrated in Figures 5'and 6. In Figure 5 the numerals 50', 51 and 52, 53 designate two pairs of reflectors in the path of the rays coming from an object which is to be stereoscopically reproduced in natural colors. '54 is an objective adapted to produce fromthe beams of light reflected from reflectors 51 and '53 superimposed images on the light sensitive to be. understood as being at the same time a diagrammatic representation of a pair of objectives separately co-ordinated to the two reflectors 52, 53. The plate 55 is provided with a color screening in the three fundamental colors of the spectrum. 56 and 57 are two P light filters, the former colored in purple and the latter in green It appears that the rays coming from the side of the filters 56 on account of their being colored in purple only affect the red and blue screen elements of the plate 55 whereas the rays coming from the side of the filter 57 on account-of their being colored in green afiect the green screen elements of the plate 55. Therefore afscree ned colored compound image is produced which contains on the same area two kinds of stereoscopically co-ordinated images, the one set represent-ed by the redand blue images and the other set by the green image. If a so obtainedscreened colored image is projected on a screen andcontemplated with spectacles withgreen and purple glasses then the one eye ofthe observer receives only the green image and the other the red and blue images, the images presented to the two that the impression of a stereoscopical reproduction of the object innatural colorsis produced.

The picture 55 could also be directly inspected with spectacles having a purple and a green glass, The picture 55 could also be used as a luminous object in connection with a device-similar to that with which it had been obtained. 1

The provision of the filters 56, 57 in the path of the rays of light allows the region of the spectrum covered by the. color screen elements to bemade broader than it could be done Without said filters. This counteracts the lo ss in, luminosity caused by the inspectionof the colored screened images with the color selectors.

In order to reduce the conflict of colors in the stereoscopic image one could in analogy to the diagram of Figure 7 use the following color regionsfor the projection of the differently colored-partial pictures; for the red picture the region of the spectrum from red at the long wave end to' yellowish green with exclusion of orange and yellow, for the green picture the pure green and blueish green and for the'blue picture the usual b'lue.

The color screening of the sensitized plate on which the images are produced could be substitiited in a manner known per so, by splitting up of the beams from' a point of the object under different conditions into comparatively small colored light pencils which are brought to action on a pain-chromatic sensitized layer. A suitable device is illustrated in Figure 6. In this figure the numerals 58, 59 and 60, 61 designate t ain as in Figure 5 two pairs of reflectors inserted into the path of the re s coming from the object'to be stereoscopical y reproduced. The rays reflected by fleetors 59, pass through the lenses of an objective 62 and on doing so pass through three color filters 63, 64, 65 arranged in the entrance pupil of the objective and then impingeon the back side of a sensitive layer carrier. This layer carrier is designated 66 and a sensitized layer'is designated 67. The back side of the transparent layer carrier 66 directed towards the objective is molded into a system of small convexly curved sect-ions' 68 which form optical systems producing each a very small image of the entrance upil of the objective 62 on the sensitized the reof light coming the image of the object is subdivided into subportions correspondinglto the three light filters 63, 64, 65 in the entrance pupil of the objective. Therefore, if the image of the object produced on the sensitized layer 67 is illuminated from the back side, that is to say, from the free surface of the image layer 67, the light passing through the image layer 67 and its carrier 66 with the lens carrying surface 68 objective 62 with the is adapted to produce a colored compound image on a screen which image can be divided up in the same way by color selectors as described with reference to Figure 5, provided the filters 63, 64, 65 are suitably and then through the colored. A suitable coloring is f. i. green,. red and blue. Y

For the purpose-of making the projection light filters 63, 64, 65

' three dilierently it is not necessary elements of the objective have exactly the same color shad as the filters 63, 64,65 throu h which the compoundimage. 0 the sensitive layer 67 was produced. i'Figures 7 to 11. show suitable color co-ordinations for v d is indicated with the letters .r! (red) the filters 63 to65 used for exposition-an those usedv for projection. A proper color 'co-ordination is the more possible as the filters are easily interchangeable. No claim is laid on the methodof splitting up of elementary portions of a photographic image by a system of small lenses such as thelenses' 68; this being known and suggested by Messrs'Keller-Dorian and Berthon.

Instead of. using a light filter device of colored sections in the en-' trance pupil of the 63, 64, 65 a filter device may be used containingfour or more sections of difierently. colored filters. This is of particular value. Assuming the compound image consists of still be mentioned that a.ny convenient formmay be used inclusive-that. of circular zones,

. the latter affording spec'al advantages with I to proper distribution of theluminosity of the image.

The method which has been described with regard to the correction of the objective and reference to Figure 5 requires the produc- 7 colors is illustrated in Figure 13. 72 two light filters inserted each containing colors,

- colore tionof color screened sensitive layers containin three or more sets of 'difierently 7 screen elements. As already has been mentioned the production of such color screened sensitive layers causes considerable difliculties. These difliculties are diminished if sensitive layers are used which are provided with acolor screening'in two colors only. An arrangement for effectively working with screened sensitive layers'the color elements .of which show'only two In this e 69 and70 are two objectives, 71 andv in the path of the light-rays coming from theobject' and 73 and 74 two-color screened sensitive layers, sections in two different the one color mixed colorcontaining two fundamental .colors'of the spectrum and the other being substantially the third fundamental color.

Suitable 'colorsfor the screen elements are.

orand'the latterin' a-mix ed color containing that the filters between the stituents and on plate 74 ob ective such .as filters.

' three partial images in'the three fundamental A5 and blue and the scopic'al reproduction. .ral colors presents i.

jected with light -71 and 72 eventually suitably shaded 'on a colors of the projecting l1 tures 73 and 74 on a;

- trated inFigure.

difierrent being substantially a mama-1o I I red and green. appear from Figur arcs of the full lines 89,90 designate those regions of the spectrum ior'which'the filters 71, 72 arepermeable. The coloration corresponding to different portions of the'lines (green)'and' 1) (blue). The arcs in te dotted. lines. 91, 92 designate the zones of colored light permeability of the purple screen elements in the plates 73, 74, and the arcs in theinterrupted lines 93, 94 the zones of-colored light permeability of the green screen elements in the same plates 73,- 74. It appears that white light becomes active on plate 7 3only with its'green and blue congreen constituents. Therefore onthe sensitive layers 73 and. 74 two stereoscopically co-ordinated images are produced, each being a compound image in purple and green, the purple partial image of the'compound image 73 corresponding'however only to the blue color aspect of the object and that of image 74 to the red color aspect of the ob- 73' and 74 are inject. If now the pictures spected by means of a stelgeoscope the former Q the kind of :the

throu h a light filter o filter 1 with ajinixed color contain 0 green latter through a lig t filter of the kind of'the .color containing red and green, then a stereo= of the object in. natuelf tot-he observer.

The pictures 73 in @the colors of thefilters be inspected through spectalsubstantially the t Instead of producing-t e-compound picscreened sensitive layer the two elementary'picscreen and then cles with glasses having in two colors so that tures of each oi the compound pictures in terlace each other,'the elementary pictures could also be produced in superposition to each other. A suitable arrangement is illusand 76 are two objectives, lightv filters co-operating with the objectives and'79, 80 and 81 a light sensitive compound,

filter 72 witha mixed.

d 74 could also be pro-' The resulting color efiects P e 12. In this figure-the I with its red and 14 of the drawingwhere 75 77 and 78twostructure consisting in the illustrated embodiment which'may be varied if desired of the non-sensitized carrier 80 and two-sensitizedlayers 79 and 81 on difi'erentsides of the carrier the two sensitized layers being sensitized tor 7 red and blue and the "layer 81 for green. is impracticableifor diflicult to sensitize a layer for. green only it is advisable to protect the la er v fluence of blue light by a yellow protective layer which prevents that blue light passing through layers 79- and reaching the layer.

difierent colors, f. i. the layer '79 mainly for In view of the fact that it 81 against unintentional in- 81. The yellow protective layer can be a separate layer or a yellow coloring of the carrier 80 or even the incorporation of a yellow dyestutf into the layer 81. If desired the layer 79 may be provided with a dyestufi which besides blue and violet absorbs also yellow and ellowish green; thereby the sensitivity ot the layer for blue light can be reduced. After exposure of the light sensitive structure 79, 80,- 81 the images are either developed as positives or the layers 7 9 and 81 are separated from their carrier and of each of them a positive is produced, such positive containing two stereoscopically co-. ordinated images of the object. Each pair of positive images is dyedwith a color corresponding to the mixture of the colors for which the sensitized layer on which the other image had been produced, had been sensitized, that is to say, the positive of the pair of images on layer 79 is dyed in green and the positive of the pair of images on layer 81 is dyed in purple, this being the mixed color of red and blue for which the layer 79 had been sensitized. The dyed positive pictures are superposed and thereafter used for producing the impression pt a stereoscopica-l reproduction of the object in natural colors. To this end the superposed images may be projected this being effected with substantially the same light with which the negatives of the superposed images had and blueish green or for the been obtained, however with differentiation of the greenish color element, f. i. for one set of two superposed pictures a mixture of red and yellowish green and for the other two superposed pictures a mixture of blue former a mixture of red and blueish green. and for the latter a mixture of blue and should be used.

Equivalent to the projection with colored light is the incorporation of color into or on the image carrying layers, may it be that the layers are dyed in their whole mass or covered with a transparent color coating. In this case the projection may be made with white light.

The pictures projected in the manner described in superposition to each other can be divided up by an observer using spectacles, the glasses of which are substantially dyed in the colorsTo-f the projecting light.

The pairs of two superposed colored pictures can of course also be used for inspection in a stereoscope and must also inthis case be illuminated with substantially the same colored light which is to beused for projection, however in this case the differentiation of. the green color element is not necessary although it is advantageous to make use of it. v Y

Also printing plates can be produced from the image carrying layers 79, 81 in the same images of this produces at a dill'erent yellowish green stereoscopical reproduction of the way as formerly described in connection with pictures of a modified nature.

In the foregoing it has been assumed that images of different color aspects of the object from the same point of view are produced on the same area whereas the stereoscopically co-ordinated images are produced on different areas. Now it is also possible to produce images of dill'erent color aspects of the object from different points of view on the same area. This possibility is of particular importance when a plurality of pictures is to be produced in succession showing the object in successive moments. Figure 15 shows apafirangement for producing In Figure 15 82 and 83 are objectives, 84 and 85 colored light filters and 86 a strip of color screened light sensitive material. he strip 86 is assumed to be subjected to a stepby-step movement, although it may also be continuously moved in connection with suitable devices for optically compensating the movement of the strip. Suitable colors for the filters 84, 85 are for instance purple and green and a suitable color screening for the strip-86 the fundamental colors of the spectrum red, green and blue. If new images are taken from the object on the strip 86 ata certain position of the strip then the light passing through filter 84 and objective 82 produces on strip 86 an affection of the red and blue screen elements whereas the light passing through filter 85 and objective 83 area of the strip an affection of the green screen elements; the two images so produced on difi erent areas of the strip are stereoscopically co-ordinate'd. If now the strip is moved so that the area which had been exposed to the light passing through filter 84 and objective 82 is brought to the position where it is exposed through filter 85 and objective 83 then on the same area of the strip an afl'ection of the green screen elements takes place so that at the same area a compound image is formed, the elements of which arestereoscopically co-ordinated, respresenting different color aspects of the object. dinated images of the object presenting different color aspects are produced on further step-by-step movement of the strip on all areas of the strip, the stereoscopically co-ordinated images presenting aspects of the object in successive moments.

The methods formerly described for making use of the color screened images for the in natural colors can be adopted. If the piet-ures are presented to the eyes of an observer in succession as they had been produced on the strip 86 then the obseryer receives the lmpression of the object as it changes in time, the method ism this case a method of Such stereoscopically co-orllO object stereoscopical cinematography in natural colors. p

I The Keller-Dorian and Berthon method for producing images for use in connection with this invention as described with reference to Figure 6 can also be used for producing. a succession of images on a movable strip with two objectives as described just now with reference to Figure 15. In -this case the arrangement ofFigure 6 is to be usedwith suitable adaptation to thepurpose. .The adaptation being'quite obvious for an expert; it needs only mentioning of onespecial point which may be explained with reference to Figure 16 of the drawing.

' In view of the factthat in this case two objectives laterally displaced with relation to each other aretobe 'used it is necessary to take'care' that the light rays passing through one objective only affect one part of the sensitized surface and that the remaining portion of each'area which has not been affected by the light during ex osition through one objective is afiected by t e'light passing through the other objective when said area of the sensitive strip is brought-into exposure positionwith relation jective. Y In order to avoid the afiecting, of the whole area of the. sensitive strip when in position'for exposition through one objective the color filters in the plane of the entrance pupil of the objectives-are so arranged that they'only are passed by the light which passes through one portion of the objectives whereas the light passing through afurtlier portion of the objectives is prevented by an impermeable screen against impinging on the 'sensitive strip. A suitablescreen arrangement is shown in Figure '16. of the drawing where the numerals 64 and.65 designite a red and a blue filter respectively and the numeral 63 agreen filter. '87 and 88 are impermeable screens arranged in the plane of the filters 63* to 65,.

the sensitive strip is provided with the small lens system as illustrated in Figur'eG and de-,

' scribed with relation thereto.-

, lVhat we claim is t 1. In a method. of streoscopical color photography the step of selecting a plurality (two or. more) of portions of light emitted from the'colored object to be stereoscopically vrepr'oduced under=difierent condi 5 tio al s forming ored image producingbeams, exposing sentitive layers with said beamssof light so as to form partial images of the object corre-' sponding. to difl'ferently coloredaspects of same and reproducing a f'partial image so more partial to the second obsensitized, screened layer to the action of In this case the original image producing beam addithereof. differently col-' produced in a co-orclinated color on a sensirality '(two or more) of, portions of light emitted from the colored objectunder different conditions and forming thereof differently colored image producing beams exposing sensitive layers with said beams of light so,as to form partial images of the object corresponding to differently colored aspects of-same and printing two or more partial images so produced substantially with the colors with which they were produced on a sensitized screened layer, the screen elements of said layer appearing in two-or more different colors.

3. In a method of sterescopical color photography the step of selecting a plurality (two or more) of portions of light emitted from the colored'object under different conditions and forming thereof differently coltire layers with said beams of light so as to form partial images of the object corresponding to difi'erently colored aspects of same and simultaneously printing two or images so produced on a sensitized screened layer, the screen elements of said layer appearing in two or more different colors.

4. In a method of stereoscopical color photography the step of selecting a plurality (two or more) of portions of light emitted from'the colored object under different conditions and forming thereof differently colored image producing beams exposing a sensitized screened layer to the action of said colored image roducing beams of light, the elements of sai layer being grouped in sets,-the different sets being acted on so as to make them appear in different colors.

5. Ina method of stereoscopical color photography the step of selecting aplurality (two or more) of portions of light emitted from the colored object under different conditions and forming thereof differently colored image producing beams exposing 'a said colored imageproducing beams of light, the elements of said ;layer' being grouped in setsof which eachhas its individual color different from the color of each other set,- one of which containing besides the color of tional colorscorresponding to-limitcd dif-' ferent portions of the-spectrum.

j 6. In? a method of stereoscopical color photography the step of selecting a plurality (two or more.) of portionsof light emitted from .the colored object under different con- 7 ditions and: forming thereof differently col ored image producing -'beamsexposing a sensitized screenlayer -to the action of said colored image producing beams of light, the elementsof said .layer being grouped in sets of which each has its individualcolor different from the color of each other set, one of which containing besides the color of the original image producing 'beam addi- .1 9

neamvo tional colors corresponding to such portions of the spectrum Which are adjacent to that portion which corresponds to the color of the original image producing beam.

7. In a method of stereoscopical color photography the step of selecting a plurality (two or more) of portions of light emitted from the colored object under different conditions and forn'iing thereof differently colored image producing beams exposing a sensitized screened layer to the action of said colored image producing beams of light, the elements of said layer being grouped in sets, the different sets being acted on so as-to make them appear in colors substantially-identical with the colors of the original image producing beams, such colors corresponding to .overlapping portions of the spectrum.

8. In a method of stereoscopical color photography the step of selecting a plurality (two or more) of portions of light emitted from the colored object under different conditions and forming thereof differently colored image producing beams exposing a sensitized screened layer to the action of said colored image producing beams of light, the elements of said layer being grouped in sets of which each has its individual color different from the color of each "other set, the colors of the image producing beams and of the sets of screen elements being so chosen and correlated that the photography the ste colors of the sets of screen elements correspond to overlapping regions of the spectrum and that each of said regions of the specturm comprises the color of one of said image producing beams whereas the region of spectrum. corresponding to the colored image producing beam is more limited than the region of the corresponding set of screen elements.

9. In a method of stereoscopical color photography the step of selecting a plurality (two or more) of portions of light emitted from the colored object under different' conditions and forming thereof differently colored image producing beams exposing a sensitized screened layer to the action of said colored image producing beams of light, the elements of said layer being grouped in sets of'which each has its individual color diflerent fromthe color of each other set, the colors of said screen elements bein such that they correspond to ortions of tfie spectrum which overla eac other, said portions: corresponding su stantially to the color of the. original image producing beams, the printing color being so selected that it can pass through one kind of the colored screen elements only which is co-ordinated thereto.

-10. In a method of stereoscopical color of selecting a plurality (two or more) 0 pictures of the other portions of light emitted from the colored object under different conditions and forming thereof differently colored image producing beams exposing a sensitized screened layer to the action of said colored image producing beams of light, the elements of said layer being grouped in sets of which each has its individual color different from the color of each other set, the colors of the image producing beams and of the sets of screen elements being so chosen and correlated that the colors of the set of screen elements correspond to overlapping regions of the spectrum and that each of said regions of the spectrum comprises the color of one of said image producing beams whereas the region of spectrum corresponding to the colored imageproducing beams is more limited than the region of the corresponding set of screen elements, the limitation being so that the region of the spectrum corresponding to the co or of the image producing beams is substantially outside the region of the spectrum corresponding to a further set of screen elements.

11. In a method of photography the step pairs of stereoscopically graphic images of the object to be reproduced with colored light, the images of the stereoscopical color of producing two co-ordinated photoof the three fundamental colors of the spectrum and both images of the other pair substantially with light in the third fundamental color dyeing both images of the one pair in a mixed color containing two fundamental colors and both images of the other pair in the third fundamental color.

12. A method of stereoscopical color photography comprising producing two pairs of stereoscopically co-ordinated photographic picturesof the object usin for each picture of one pair one of the three fundamental colors of the spectrum and for both pictures of the second pair that fundamental color of the spectrum which had not been made use of in producing the first pair, dyeing the first pair in the last named color and the' second pair in a mixed color containing the other two fundamental colors.

13. A method of stereoscopical color photography comprising producin two pairs of stereoscopically co-ordinated ilrotographic pictures using substantially red and blue ight for producing the pictures of the one pair and substantially green light for both pair, dyemg the first pair with green and the second pair with purple color and superposing the said two pairs of uniformly colored images.

14. A. method of stereoscopical color photography comprising producing two pairs of stereoscopically co-ordinated photographic images in en erimposed transparent sensitive layers 0 which the front layer is sen- 'sitized substantially for red and blue li ht ,andthe back layer substantially accessi le to green light only but protected against red and blue light, the exposure being effected for the one image of the pairs with a red and a green colored light mixture and for the other with a mixture of green and blue light, dyeing the pictures of the front layer with green color and those of the back layer with purple color.

15. A method of stereoscopical color photography comprising producing two sets of stereoscopically co-ordinated images, the one set consisting of a plurality of images, the images being obtained by exposing the respective sensitive layers with difierently colored kinds of light. I

16. A' method-of sterescopical color photography comprising producing a plurahty of photographic images of the. object form-- a ing two sets of stereoscopica-lly co-ordinated images, the one set consisting of three images each obtained by exposlng a sensitive layer with light of one fundamental color substantially.. 17. A stereoscopic picture comprising a plurality of interlacing partial images of an object to be stereoscopically reproduced whereof at least two interlacing images are stereoscopically co-ordinated to each other. 18. A stereoscopic picture comprising a plurality of interlacing partial images of an object to be stereoscopically reproduced, said plurality of the partial images comprising at least two images representing aspects of the object at different moments, two or more of the interlacing images being stereoscopically co-ordinated.

' 19. A stereoscop1c plcture comprising a plurality of interlacing partial images of an object to be stereoscopically reproduced, said plurality of the partial images comprising at least two images representing aspects of the object at different moments, at least two of said last named images being stereoscopically co-ordinated to each other.

20. A compound picture for stereoscopic reproduction of an object comprising two partial images on the same area the one in purple and the other in green color.

21. A compound picture for stereoscopic reproduction of an object comprising two interlacing partial images on the same surface the one in purple and the other in een color.

22. A picture for stereoscopic reproduction of an object comprising two compound images in lateral co-ordination to each other, each compound image consisting of two images, the one purple and the other in green color the two compound images being stereoscopically co-ordinated to each other.

23. A picture for stereoscopic reproduction of an object comprising two compound images in lateral co-ordinationto each other,

. two images each compound image consisting of two interlacing partial images on the same area the one purple .and the other in green color, the two compound images being stereoscopically co-ordinated to each other.

24. A compound picture for stereoscopic reproduction of an object comprising two partial images on the same area, the one colored substantially in of the spectrum and the other colored in a mixed color containing substantially the two other fundamental colors of the spectrum.

25. A compound picture for stereoscopic reproduction of an object comprising two interlacing partial images on the same surface, the one colored substantially in one fundamental color ofthe spectrum and the other colored in a mixed color containing substantially the two other fundamental colors of the spectrum.

26. A compound picture for stereoscopic reproduction of an object comprising two partial images on the same area, the one colored substantially in one color of the spectrum and the other colored in a mixed color containing substantially the two other fundamental colors of the spectrum, the field where the two partial images are provided being colored in a mixed color containing at least partly the color of that image which is colored in the one fundamental color and at least partly the color of one of the two fundamental colors contained in the coloring of the second image.

27. A compound picture for stereoscopic reproduction of an object'comprising two interlacing partial images on the same surthe one colored substantially in one two partial images are provided being colored in a mlxed color containing at least partly the color of that image which is colored in the one fundamental color and at least partly the color of one of the two funfundamental one fundamental color damental colors contained in the coloring of the second image.

28. A picture for stereoscopic reproduction of an object comprising two compound in lateral co-ordination to each each compound image consisting of the one purple and the other in green color the two compound images being stereoscopically co-ordinated to each other, the fields where the two compound images are provided bein colored in mixed colors, the mixed color 0 the one containing green gpd red and that of the other green and 29. A picture for stereoscopic reproduction of an object comprising two compound images in lateral co-ordination to eachother,

images other,

the two compound images being stereoscopically co-ordinated to each other, the fields where the two compound images are provided being colored-in mixedcolors, the mixed color of the one containinggreen and red and that of the other green and blue. 30. A picture for stereoscopic reproduction of an object comprising two compound images in lateral co-omiination to each other, each compound image consisting of 7 two images theone substantlally in one fundamental color and the other in amixed color containin substantially-the two other fundamental co ors of the spectrum, the elementary images of at least oneof the compound-images being stereoscopically co-ordinated to each other and at least one of them being stereoscopically co-ordinated to at least oneof the elementary images of the other compound image. 7

In testimony'whereof, we afiix our signatures.

DR. GARLMULLER. ELSA MULLER. 

